A. Field of the Invention
The present invention relates to the field of network management, and more particularly to the use of managed objects to communicate with unknown devices.
B. Background of the Invention
The Small Network Management Protocol (SNMP) provides network managers with ways to manage the ever-growing complexity of networks. Networks may contain many different types of devices such as, repeaters, modems, bridges, routers and computers. Each device may contain numerous hardware and software components that affect network performance. Each type of device may be manufactured by any number of network component vendors. The SNMP provides a way for network managers to organize the massive amount of information needed to manage multi-vendor networks. For example, network management involves working with many variables that need to be defined, described and named.
A tree structured framework called the Structure of Management Information, or SMI, provides a way for defining administrative relationships, organizing network management data and assigning an identifier to every network management variable. In addition, the SNMP uses a template called Management Information Base (MIB) for defining network management variables. Network management variables are referred to as network management objects which have a name, attributes and a set of operations that can be performed on the object. A MIB consists of a set of managed objects. General examples of managed objects include a system description, a number of incoming bytes received at an interface, and the IP address assigned to an interface.
MIBs provide a convenient way to organize network information. In addition, the International Organization for Standardization (ISO) and the International Telegraph and Telephone Consultative Committee (CCITT) have instituted a global naming tree and a way of assigning identifiers to any object that needs a name. As new devices or network components are made available, MIB objects or groups of objects may be defined and added to this global tree. The advantage of using this global tree is that it provides a standard way of receiving and modifying management information on any network device. In addition, once a MIB exists in the global tree for a device, an SNMP manager can communicate with it.
MIBs are used in networks that include a managing station that has a manager program. The managing station communicates with devices on the network having programs called agent programs. Managers and agents communicate using a set of commands, or message types. For example, a GET-request message type retrieves one or more values from a managed nodes MIB. A set-request enables the manager to update appropriate variables. And a response message type returns the results get-request or set-request operation. A trap message type enables an agent to spontaneously record important events or problems. Managers and agents communicate with each other by transporting message types using one of any number of communications protocols. On commonly used protocol is a user datagram protocol (UDP).
An example of a network that uses the SNMP may include a computer having a manager program connected to a bank of modems, each having agent programs. The computer also includes an application program that provides a user with an interface for executing commands that manipulate MIB objects. One example of such an application includes the Hewlett-Packard Openview application.
Some devices may use MIBs that have been defined for particular classes of devices. For example, a modem may use MIBs defined in the "Modem Management Information Base using SMIv2" standard found in Request for Comments 1696 (RFC). RFC 1696 is hereby incorporated by reference.
One problem with using MIBs is that selected devices may be updated to include new features and capabilities that are not reflected in the known MIB for that device. Those features or capabilities may not be available to a manager until the MIB is updated. In addition, managers may determine a need to perform previously unforeseen duties relating to the management of selected devices. If these unforeseen duties are not supported by the MIB definition, they may not be performed until the MIB is updated. For example, a modem having a MIB defined for it may be updated to include new features and capabilities. These features and capabilities are not known to an SNMP manager until the MIB is updated to incorporate managed objects that make use of these features.
It would desirable to have the capabilities of extending the features and capabilities of MIB objects without having to add any new objects.